The invention relates to an impact protection device for an occupant of a motor vehicle having an air bag which is arranged folded up in a receptacle fixed to the vehicle and which can be inflated by means of a filler gas, an air bag surface facing a vehicle occupant being limited in its movement towards the vehicle occupant by a restraining device in the center region, which restraining device includes a holding part which rests against the air bag and is connected to the vehicle via limiting straps.
In German Pat. Document No. DE-PS 21 52 902 an impact protection device for the occupant of a motor vehicle is described, which comprises an air bag to which an internal restraining device is assigned which limits the expansion of the air bag towards a vehicle occupant. The restraining device is formed by an impact surface connected to the air bag and by cables holding the said impact surface. The additional necessary impact surface part must be fastened to the air bag from inside. Due to the long limiting straps (cables) an unfolding momentum of the center region of the air bag towards the vehicle occupant is still possible.
The German DOS 19 54 398 shows a protection device with a foamed material which expands in the event of danger and on which a cover cap of the protection device continues to be seated on the expansion of the foamed material. This cover cap does not limit the expansion of the foamed material towards a vehicle occupant and is also moved to the greatest extent in the direction of the vehicle occupant.
The invention is based on the object of advantageously using a device part, customary in an impact protection device, for a restraining device of the generic type mentioned above.
The object is achieved by means of an arrangement wherein the holding part is formed by a cover plate for a receptacle for the folded up air bag and wherein the limiting straps are limited in their length in such a way that the cover plate is covered in the direction of the vehicle occupant by the inflated air bag.
By means of the short limiting straps, which permit only a lateral emergence of the air bag at the periphery around the cover plate, it is achieved that after the unfolding of the air bag in the direction of the vehicle occupant the cover plate remains behind the air bag. In this respect it is particularly cost-effective that the existing cover plate which is already required and which covers the folded up air bag in a receptacle fixed to the vehicle can be used as a restraining device.
Furthermore, by means of the design or of the materials of the limiting straps it can be achieved that upon the stressing of the cover plate the straps have to be shortened again by the vehicle occupant with a consumption or degradation of energy. As a result, the stress on the occupant is in turn reduced in the event of a secondary impact against the cover plate. Here, limiting straps are to be designed to correspond to folded steel straps or even as springs, preferably damped.
The cover plate can also be connected to keep the air bag from slipping out from the cover plate on one side, which, due to the fact that the cover plate is seated on the outer surface of the air bag, requires no expenditure.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.